I did some digging around about the actual material used in cannulas that infuse insulin. I could not find the definitive answer but it appears to me that infusion cannulas are made of either steel or teflon. Here’s some narrative from one 2018 study that talks about the two cannula styles as it was looking at inflammation when using these different cannulas.
Continuous subcutaneous insulin infusion (CSII) catheters are the most crucial part of insulin pump therapy for insulin dependent patients1,2,3,4,5. They have been on the market since the late 1980s and are manufactured with both Teflon (polytetrafluoroethylene) and steel cannulas[6]
(Systematic in vivo evaluation of the time-dependent inflammatory response to steel and Teflon insulin infusion catheters | Scientific Reports),7. The choice of one material over the other is largely based on the patient’s personal preference, his or her endocrinologist’s or diabetes educator’s opinion and therapy costs8,9,10. There is a trend in both the United States and Europe towards using Teflon sets (90% and 75%, respectively) but approximately 40 to 45% of pump users in Germany use steel catheters4,8,11. Compared to Teflon, steel catheters are easier to insert and are less prone to kinking, and can be worn by patients allergic to Teflon. Patients using steel catheters report better metabolic control, less variable insulin absorption and less unexplained hyperglycemia8,12. However, especially during exercise, steel may cause discomfort and the softer and more flexible Teflon catheter is assumed to be more comfortable to wear8,13,14.
When I visited the Medtronic web site I did a search on their line of infusion sets and found that every set described their non-steel cannulas as “soft plastic cannula.” I searched using the word, teflon, and it came back empty.
I then did a Google search on teflon and found several items coming back talking about the controversy of the negative health effects of using teflon in cookware. Now I do remember some media coverage about people switching away from cookware with the teflon non-stick coating since they thought it was unhealthy.
I don’t know the answer to whether a teflon frying pan is bad for your health but I think that the marketing people at Medtronic and other infusion set suppliers decided that they didn’t want to use the term, teflon, anymore since it had too much controversial baggage.
I don’t think, however, that the cannula material changed, at all. I think it is teflon that is now marketed to us as soft plastic. Same thing, different terms.
It makes sense to me that teflon is used for this purpose. Think about it. The cannula fits like a sleeve around the introducer needle and follows it into the subcutaneous tissue. When the introducer needle is withdrawn, the last thing desired is for the cannula to stick to the withdrawing needle and then become kinked. Teflon is a logical choice for this material as its slipperiness is what is is known for.
